You should be able to find plenty of decent hardtail low-end mountain bikes in the $500 - $900 range, particularly if you wait until the off-season to do your shopping.
My personal advice would be to buy your way into a decent frame and upgrade components as they fail. If there's one thing I found from several years of avid mountain biking, it's that parts wear and break much faster than they do in road riding, giving plenty of upgrade opportunity. :-)
That's not quite accurate. Here's a random example:
http://www.rei.com/c/mountain-bikes
You should be able to find plenty of decent hardtail low-end mountain bikes in the $500 - $900 range, particularly if you wait until the off-season to do your shopping.
My personal advice would be to buy your way into a decent frame and upgrade components as they fail. If there's one thing I found from several years of avid mountain biking, it's that parts wear and break much faster than they do in road riding, giving plenty of upgrade opportunity. :-)